I was converted to the Medtronic after using a Libre. The one big huge advantage is that in combination with the 640G, the Smart Guard feature has cut down the number of hypos substantially. The pump just shuts down if it calculates that your heading for a hypo and then restarts when you're rising again.
You don't need a starter pack as such. You need to buy a transmitter, which is a big outlay, and then after that it's the ongoing cost of the sensors. The transmitter is supposed to last for one year, but I understand that most people find they last for much longer. And the sensors are supposed to last for six days, but I seem to make my last for longer. I think that Medtronic says that they are only reliable for six days and that their accuracy drops after that. Overall, it's more expensive than the Libre but in practice not as much as would appear on paper.